Challenges encountered while constructing the world's largest spar

The Holstein truss spar hull and mooring, the largest ever built, was constructed in 24 months, beginning in April 2002. Due to its size, it could not be dry transported in a single piece. Thus, the hull was constructed in two yards, in Finland and the U.S. The dry tow from Finland was followed by a unique launch and wet mating prior to wet tow to site. Extraordinary measures were required to accomplish the project requirements. Some of the challenges encountered are described from a technical viewpoint and mitigations provided.